1. Field of the Invention
The invention relates to processes for welding along a horizontal groove, more particularly to a submerged arc welding process and to a particular flux dam which is useful in such a process as well as to an improved method of submerged arc welding. Also, the invention relates to the use of such a dam in other welding processes, e.g., electroslag welding.
2. Prior Art
It has been known in the prior art to use a flux dam in welding processes such as submerged arc and electroslag welding wherein the flux dam is used to retain a molten slag blanket over a pool of a molten weld metal along a horizontal weld groove. A number of problems however exist with such prior art flux dams. For example, one common prior art flux dam is a copper strip which is generally held in place by a clamp or the like. Unfortunately, copper strips tend to stick to the flux thus causing removal problems. Also, the clamps which hold the copper strips in place necessarily block at least a portion of the non weld-abutting side of a vertical workpiece which with an abutting workpiece forms a horizontal weld groove. Another common prior art flux dam comprises copper shoes on a moving belt with the shoes progressively contacting the vertical workpiece adjacent the electrode in the horizontal weld groove. A serious problem is created especially in more modern computer controlled welding wherein a sensor is used to sense the horizontal weld groove and a signal from the sensor is used to direct the movement of an automated welding electrode. In such a situation the clamps for the copper strips or the shoes-belt apparatus can get in the way of the sensor or its associated apparatus and thus interfere with such programmed welding. Also, if a metallic (copper, etc) flux dam is used this can electrically interfere with sensor operation. Further, the copper strips used as flux dams while they do have some flexibility, are often not sufficiently flexible to match some of the more highly erratic weld grooves which must be welded. Still further, even if the copper shoes are sufficiently flexible to match such a weld groove for one or a few uses, the copper soon becomes embrittled by constant bending thereof into different shapes and hence new copper strips must be used as replacements while the old copper is recycled.
The demands of modern technology are such that welds must be made along complex curves and, further, automated control of submerged arc and electroslag welding is necessary to insure its uniformity and to insure that welds can be made quickly. Thus, the abovementioned problems which are not solved by the prior art copper strips or shoes are indeed serious. A practical and inexpensive solution of such problems would be highly desirable.